Rt cylinder damage

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Re: Rt cylinder damage

Post by Crawford Sales Co. » Tue Aug 25, 2020 10:43 pm

What does the head look like? If there was something in there beating up the piston the head would also look pretty bad. Got any pictures?
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Re: Rt cylinder damage

Post by windmill » Tue Aug 25, 2020 11:40 pm

I've had piston damage like that on a Gravely tractor. looks more like a failed ring than FOD, or detonation to me.
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Re: Rt cylinder damage

Post by PhilJet09 » Wed Aug 26, 2020 2:50 am

PhilJet09 wrote:
Mon Aug 24, 2020 8:40 pm


Image

Just impact damage from the broken ring in the head. I had it sitting upside down on the bench for a couple hours with mineral spirits in the dome, covering both valves. It didn’t leak a bit past the valve seats, so I might have gotten lucky there. Tomorrow I’ll get out my valve spring compressor and have a look at the seats and valve faces for damage.
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Re: Rt cylinder damage

Post by Snakeoil » Wed Aug 26, 2020 11:21 am

Well, interesting how that much of the ring could escape with that little of the land missing. In those last pictures, there does appear to be a bit of a mottled surface where the land failed. But not what I would expect to see for the ultra-high temps present during detonation.

You may have simply failed a ring when you first noticed that drop in idle RPM. The compression would have been lower in that jug as a result. The piece slowly chewed its way into the groove and land until it finally snagged and... well... you know the rest of the story. You can see where that piece of ring flopped back and forth (well, up and down, really) with each stroke of the piston until it tunneled its way out.
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Re: Rt cylinder damage

Post by PhilJet09 » Wed Aug 26, 2020 12:43 pm

Snakeoil wrote:
Wed Aug 26, 2020 11:21 am
Well, interesting how that much of the ring could escape with that little of the land missing. In those last pictures, there does appear to be a bit of a mottled surface where the land failed. But not what I would expect to see for the ultra-high temps present during detonation.

You may have simply failed a ring when you first noticed that drop in idle RPM. The compression would have been lower in that jug as a result. The piece slowly chewed its way into the groove and land until it finally snagged and... well... you know the rest of the story. You can see where that piece of ring flopped back and forth (well, up and down, really) with each stroke of the piston until it tunneled its way out.
Yep, that’s what I’m thinking happened as well. I’m considering taking the other side off to make sure all is well. It’d suck to get the bike back together only to have it happen again on the left side. Probably little chance, but I’m going to be waiting for parts anyway.

Here’s a question I’ll pose to the collective - should I replace the head? The valves seal, seats and valve faces are in great shape. I can clean up some of the damage in the aluminum from the ring, kinda smooth out the craters. The mating surfaces are fine. Am I asking for trouble here? Maybe I should just replace it. I’m not made of money, but I do want the bike to be as reliable as possible. Plus, I hate doing the same job twice.
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Re: Rt cylinder damage

Post by Lokiboy » Wed Aug 26, 2020 1:07 pm

I’m not a mechanic, but IMHO, if there is no significant damage, I’d just replace the piston & rings.
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Re: Rt cylinder damage

Post by heindlengineeringural » Wed Aug 26, 2020 1:09 pm

We have seen some of these before. Sometimes the head needs replaced, other times not. If the valves/valve seats are good it is not 100% necessary to replace the head. Pay close attention to the bore on the cylinder as that can be damaged as well.
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Re: Rt cylinder damage

Post by Snakeoil » Wed Aug 26, 2020 5:11 pm

If it were mine, I'd blend out the damaged areas as little as possible and run it. Don't leave anything that could cause a hot spot. You really have nothing to lose. If the head fails (struggling with how it would/could) what's the worst case scenario? Big crack, no compression? Piston will not even know it failed. So, you'll just need a replacement head in that case.

Run it.
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Re: Rt cylinder damage

Post by PhilJet09 » Wed Aug 26, 2020 7:15 pm

Talked to Heindl today and that is the game plan. Ordered parts today, should be here tomorrow. Can’t get much better than that!
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Re: Rt cylinder damage

Post by PhilJet09 » Fri Aug 28, 2020 12:22 pm

Image

All back together. Test ride and leak check good!
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Re: Rt cylinder damage

Post by cookiemech » Fri Aug 28, 2020 12:40 pm

That's gettin' 'er done! Glad to hear it!
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Re: Rt cylinder damage

Post by Snakeoil » Fri Aug 28, 2020 12:58 pm

:cheers: Well done!
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Re: Rt cylinder damage

Post by PhilJet09 » Fri Aug 28, 2020 1:39 pm

Thanks. Best part is, it kick starts easy again. I guess I should have at least done a compression test when the symptoms got worse.
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Re: Rt cylinder damage

Post by Mr Wazzock » Fri Aug 28, 2020 7:00 pm

:clap:
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